Powder train interrupter



Jan. 16, 1951 L.. M. ANDREWS 2,537,953

POWDER TRAIN INTERRUPTER Filed Dec. 14, 1943 2 Sheets-Sheet 1 aai;

0F A065 LE RA TION INVENTOR `ATT RNEY Jaun.` 16, 1951 L.. M. ANDREWS 2,537,953

POWDER TRAIN INTERRUPTER Filed Dec. 14, 1943 2 Sheets-Sheet 2 INVENTOR LAURENCE M. ANDREWS Patented Jan. 16. 1951 POWDER TRAIN INTERRUPTER Laurence M. Andrews, Washington, D. C., assigner to the United States of America as represented by the Secretary of the Navy Application December 14,1943, ,Serial No. 514,243

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 3 Claims.

This invention relates to inertia-operated powder train interrupters for use in projectile fuzes, and more particularly to a device wherein a squib remains blocked from a booster until .the projectile has traveled a safe distance from the gun, at which time a communicating passage is established between the squib and the booster charge. One object of this invention is to provide a safety device for projectile fuzes for positively maintaining an explosion discharge passage in blocked condition until the projectile containing the device is fired from a gun and the device is acted upon by setback. Upon ring of the projectile and after a delay which is interposed for purposes of safety, a connecting discharge passage is established between a squib and a booster charge, thus arming the device.

A further object of this invention is to provide a device of the character described which cannot be accidently armed by dropping or jolting and which operates only after actuation by a sustained force or" setback and substantial cessation of `the force of setback.

A further object of this invention is to provide a device of the character described which is simple in operation and manufacture, and positive in action.

These and other objects of the invention will be apparent from the following description and the attached drawings,` in which:

Fig. 1 is a front elevational View of one form of the device, partly in section, showing the parts in their initial unarmed positions;

Fig. 2 is a side elevational view, partly in section, of the device shown in Fig. l;

Fig. 3 is a cross-sectional view taken on line 3-3 of Fig. 1;

Fig. 4 '1s a cross-sectional view taken on line 4-4 of Fig. 2;

Fig. 5 is a View similar to Fig. 1 but with the parts in their iinal armed positions; and

Fig. 6 is a plan View of the device.

The safety device. as shown, comprises a cupshaped lower base Ill which is externally threaded at its lower end for mounting on other parts of the fuze. A passage I I extends longitudinally through the closed end of the base. Near the upper end of the base, its inner diameter is enlarged to form a shoulder I2, and a thin walled cylindrical casing I3 is positioned on the upper end of the base. A support I4, having a cylindrical base portion I5, rests on shoulder I2 and is held in position by a lug I5a on base member II), or by other suitable means. The upper portion of support I has a generally semi-circular cross-section, as shown in Fig. 4, and has a slot Ida through which wires Ib extend from terminals I Ea, on the upper end of support I4, to a squib (not shown). Support I4 has a squib receiving cavity I6 in its lower portion whichV is connected by passage I1 to the lower surface of the support. Passage I1 is positioned so as to lie directly over the opening II in base member I0. The base I5 of the support has a longitudinal passage I8 extending therethrough near its periphery. A shaft I9 extends upwardly from the center of base member Il! and is held in place byl screw 20, the shaft projecting to the center of the lower portion I5 of the support and being held thereon by a screw 2l. A stud 22a extends downwardly from the lower surface of support I5 for a purpose which will be explained Y has a longitudinal passage 25, extending through it for a purpose which will be explained below.

Attached to the upper surface of base I5 of the support by means of screws 28 is an inverted U-shaped guide 21 having an opening in its upper portion which is aligned with passage I 8 in the base I5. A pin 29 carrying a weight 30 is positioned in guide 21, the pin extending upwardly a short distance through the opening in the guide and extending downwardly through passage I t and into passage 26 in the rotor, thus preventing rotation of the rotor. A spring 3! bearing against the weight 3l) and the upper surface of support I5 tends to push-pin 29 upwardly out of the passage 25 in the rotor.

Mounted on a transverse shaft 320. carried by support IQ and rotatable together are a notched wheel 352, a disc pcarrying a peripheral weight 3G, and a cam 35 which has a cut-away portion 35a. A spring 36 attached at one end to guide 21 and keyed to the cam 35 at its other end tends to rotate the cam, and the members which rotate with the cam, in a counter-clockwise direction, thus tending to maintain them in the position in which they are shown in Fig. l. When the cam is in its initial position as shown in Figs. 1 and 2,

it engages and prevents upward-movement of pin 29, thus retaining pin 29 in its locking position so as to prevent the rotor from being rotated by spring 24. A portion of the notched wheel 32 is cut away to form a shoulder 31 which is adapted to engage a resilient latch 38 attached to support ld by screw 39.

Rotatably mounted on a shaft io journaled in support le is a weight 4l which carries pins 2 and 43 adapted to engage the notches on wheel 32 to provide an escapement. The engagement of pin 42 with the last notch on the notched wheel, as shown in Fig. 1, acts as a limit of counter-clockwise movement of the notched wheel and cam.

In operation, the parts of the device before acceleration are in the position shown in Figs. 1 and 2. Due to the fact that the passage 23 in rotor 22 is not inV alignment with passages i1 and Il, premature ring of the squib (not shown) in cavity I6 cannot detonate the booster charge (not shown) to which passage H leads, and, therefore, the device is unarmed. Rotor 22 is retained in its unarmed position by pin 29 which extends into opening 2e in the rotonthe pin being held against upward movement out of opening 26 by cam 35 against which the upper end of the pin is urged by spring 3i. Notched wheel 32, disc 33, and cam 35 are urged in a counter-clockwise direction as seen in Fig. 1, by spring 36 but are unable to move in that direction due to the fact that pin 42 engages the end notch on notched wheel 32.

When the device is accelerated in the direction of the arrow in Fig. l by ring a projectile containing it, the force of setback acting on weight 34 rotates the weight, disc 33, notched wheel 32, and cam 35 in a clockwise direction as seen in Fig. 1, thereby rotating the cut away portion 35a of cam 35 into position over the upper end of pin 29. This rotation is delayed by the escapement device comprising notched wheel 32 and pins 42 and 43 on the oscillating weight 4|. On reaching the position shown in Fig. 5, notch 31 is engaged by latch 38 which retains the cam in its position shown in Fig. 5, against the action of spring 35.

The force of setback resulting from acceleration of the device also acts on weight Sil on pin 23, tending to force pin 29 downwardly against the resistance of spring 3|, the weight and pin being held down as long as the force of setback is greater than the force of spring 3|. When the acceleration and the resulting force of setback diminish suiciently, pin 29 is pushed up-wardly by spring 3! into the cut away portion 35a of the cam, thus moving the lower end of the pin out of passage 26 in the rotor. The pin 29 thus releases the rotor, and the latter is rotated by spring 24 to its armed position determined by stud 22a on sup-port l5. In this position of the rotor, passage 23 is aligned with passages Il and I1, thus establishing a discharge passage between the squib and the booster charge. The device is now in armed condition.

The downward movement of pin 29 on acceleration of the device moves the pin out of contact with the surface of cam 35, thus preventing friction between the upper end of the pin and the surface of the cam when the latter rotates. This downward movement of pin 29 also assures that it will retain the rotor 22 against rotation during acceleration of the device, thus providing a further safety feature.

The delay between firing the projectile and arm-ing of the device, interposed by the escapement mechanism and by the downward movement of pin :29 .by setback, is an important feature of the invention for it assures that the projectile is bore safe.

The spring 3B returns the escapement wheel 32 and the cam 35 to their initial unarmed positions after any slight rotation of those elements which is insuiiicient to vengage latch 38 and shoulder 31, and, therefore, the device cannot be accidentally armed by minor accelerations such as those caused by dropping or jolting, nor will such accelerations have a cumulative effect. The retarding action of the escapement is also important in preventing accidental arming of the device, and vit Vassures that the device will remain unarmed except when acted upon by the sustained acceleration Vof substantial magnitude caused by firing the projectile from a gun.

The invention described herein may be manufactured and use by or for the Government of the United States of America for governmental purposes without the payment 0f any royalties thereon or therefor.

1 claim:

1. An inertia operated device for an ordnance fuze having an ignition conducting passage, the combination including yan element supported for rotation about a first axis extending longitudinally in a direction parallel to the direction of the acceleration applied to said fuze and offset from said passage whereby a portion thereof is interposed within said passage, said element being rotatable from an unarmed position wherein the interposed portion of said element blocks the continuity of said passage to an armed position wherein the interposed portion of said element forms a continuation of said passage, biasing means tending to cause rotation of said element to its armed position; a pin supported parallel to said longitudinal axis having an end thereof engaging said element for retaining said element locked in an unarmed position, a peripheral cam secured to a shaft rotatable about a second axis normal to said first longitudinal axis and having its peripheral surface positioned for engagement with the other end of said pin, biasing means forcing lsaid pin into engagement with said surface whereby upon .rotary movement of said cam said pin will be moved by said biasing means for retaining engagement with said rotatable element, an inertia responsive means comprising a notched disk having an arcuate mass secured to one side thereof oiset from said axis operatively connected to said shaft and rotatable about said second axis in response to sustained linear acceleration of said fuze, and biasing means for rotating cam in a direction opposite the direction of rotation by said inertia whereby said fuze will be armed only by the application of sustained linear acceleration.

2. The combination dei-ined in claim 1 including an inertia member secured to said pinV for moving the end of said pin out of engagement with the surface of said cam during acceleration of said fuZe whereby to prevent friction drag on said surface.

3. The combination defined by claim 2 char.- acterized further by the addition thereto o f an escapement mechanism comprising a -pivoted member having laterally extending pins for engagement with the notches in said disk for delaying the rotation of said inertia means about its axis.

LAURENCE M. ANDREWS.

(References on following page) 5 REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Number Name Date Schenk Mar. 7, 1939 Honger 1 Dec. 12, 1939 McCaslin Aug. 31, 1948 FOREIGN PATENTS Country Date Great Britain Aug. 27, 1926 

